Fuel pump

Abstract

A fuel chamber is formed between a pump arrangement and a motor arrangement, and outer flow passages are formed between a stator of the motor arrangement and a housing. Fuel, which is discharged from a discharge port of the pump arrangement, is outputted to an outside of the housing from a fuel discharge conduit that is formed on a side of the motor arrangement, which is opposite from the pump arrangement, after passing through the motor arrangement. At a time of performing electroplating on the stator, electrode contact portions, to which electrodes can contact, is formed in an outer wall of the stator, which forms the outer flow passages.

The invention claimed is: 
     
       1. A fuel pump comprising:
 a pump arrangement that has:
 a casing that includes a pump chamber, wherein the pump chamber is communicated with a suction port, through which fuel is drawn into the pump chamber; 
 an impeller that pressurizes the fuel in the pump chamber; and 
 a discharge port that discharges the fuel, which is pressurized through rotation of the impeller, from the pump chamber to an outside of the casing; 
 
 a motor arrangement that has:
 a rotor that is placed on one axial side of the impeller of the pump arrangement and rotates the impeller; and 
 a stator that is configured into a ring form and is electroplated, wherein the stator is placed on a radially outer side of the rotor; 
 
 a housing that is configured into a tubular form and is placed on an outer side of the stator, wherein the housing forms a fuel chamber at a location between the pump arrangement and the motor arrangement, and the housing forms an outer flow passage on the outer side of the stator; 
 a fuel discharge conduit that is placed on an opposite side of the motor arrangement, which is opposite from the pump arrangement, wherein the fuel discharge conduit discharges the fuel, which flows from the discharge port of the pump arrangement through the motor arrangement, to an outside of the housing; and 
 an electrode contact portion, which is formed in an outer wall of a stator core of the stator that forms the outer flow passage, wherein: 
 the outer wall of the stator core includes a plated metal surface, which is electroplated on a surface of a magnetic material of the stator core at the outer wall of the stator core; and 
 the electrode contact portion is an exposed area of the plated metal surface, the exposed area of the plated metal surface is a trace of contact of an electrode to the outer wall of the stator core at a time of performing electroplating and is thereby not plated to expose the magnetic material at the outer wall of the stator core. 
 
     
     
       2. The fuel pump according to  claim 1 , wherein:
 the stator includes a coil, which is wound around the stator core; and 
 the electrode contact portion is formed in the outer wall of the stator core, which is located at an outer side of the stator core in a radial direction. 
 
     
     
       3. The fuel pump according to  claim 2 , wherein:
 the fuel pump is configured to be placed in a fuel tank; 
 the motor arrangement is configured to be placed at an upper side of the fuel pump in a direction of a gravitational force in the fuel tank, and the pump arrangement is configured to be placed at a lower side of the fuel pump in the direction of the gravitational force in the fuel tank; and 
 the electrode contact portion is placed on a side of an axial center of the stator core where the pump arrangement is placed. 
 
     
     
       4. The fuel pump according to  claim 1 , wherein a distance between the housing and the stator, which form the outer flow passage, is set to a value that enables suctioning of the fuel from the fuel chamber by a surface tension. 
     
     
       5. The fuel pump according to  claim 1 , wherein the electrode contact portion is placed in a location, which is other than a location that is immediately above the discharge port of the pump arrangement in a direction of a gravitational force. 
     
     
       6. The fuel pump according to  claim 2 , wherein the stator core is configured into a polygonal form in a view taken in an axial direction, and a plurality of corners of the polygonal form of the stator core contacts an inner wall of the housing. 
     
     
       7. The fuel pump according to  claim 2 , wherein the stator includes a partition, which extends in an axial direction at a location that is between the stator core and the housing. 
     
     
       8. The fuel pump according to  claim 1 , wherein:
 the stator includes a resin portion made of a resin material; and 
 tin plating is used as the electroplating.